Process for electrolyzing alkali-chlorid solution.



W. GAUS.

PROCESS POR ELEGTROLYZING ALKALI CHLRIDSOLUTION.

APPLICATION FILED Nov.11, 1912.

, 1,12,627, l Patented Jan.26, 1915.

` cathode space, that is,

Jstance,

WILHELM Gnus,

0F LUDWIGSHAFEN-ON-THE-RHINE, GERMANY, ASSIGNOR TO` BADISCHE ANDLIN & SOIDAI/EABRIK,- 0F LUDWIGSHAFEN-ON-THERHINE,

GERMANY, A CORPORATION.

PROCESS FOR ELECTROLYZING ALKALI-'GHLORID SOLUTION.

Specification of Letters Patent.

Patented-Jan. 26, 1915.,

Application led'November 11, 1912. Serial 'No.`730,`753.

To all whom it may concern Be it known l*that I, W'ILHELia GAUs, lsubject of the King of Prussia, residing at Ludwigshafen-on-the-Rhine, Germany, have invented new and useful Improvements in Processes for Electrolyzing Alkali-Chlorid Solution, of which the followingv is a speciication.

During the electrolysis of alkali chlorids there is 'always a tendency for 'hydroxyl ions to wander, together with the clilorin ions, from the cathode space to the anode space and this tendency is greater when the cathodic decomposition is pressed in order to obtain a liquor as free from salt as possible. The presence of these hydroxyl ,ions at the anode is disadvantageous rise to oxygen and diminish the yield and also attack the anode, which is generally made of carbon. To prevent, as far as possible, this wandering of the hydroxyl ions, a so-called filter diaphragm has been employed which is easlly permeated by the electrolyte, and salt solution has been allowed to pass continuously through this filter diaphragm from the anode space to the in a direction opposite to that in which the hydroxyl ions move and, under certain conditions of motion of4 the electrolyte, it is possible to retain most of the hydroxyl ions in the cathode space. The actionof the said filter diaphragm is, however, unsatisfactory on account of the varying size of the pores and consequently the diierent rate of low through the various pores: Other methods have vtherefore also been employed with the view of preventing as far as possible the intrusion of the hydroxyl ions into the anode space. For init has been proposedto wash away the cathode liquor immediately by means of water or steam, or to convert it into carbonate by blowing in carbon dioxid and thus diminish the concentration of the hydroxyl ions. It has also been proposed to mix the alkali drops which form at the cathode with Va non-conductive oil, so as to form an emulsion and thus withdraw them from the fur- `jthervaction of the electric current. These -hods all have disadvantages.

vpresent invention relates to processes ich alkali chlorid solution is electrolyzedfin vertical cells, that.' is, cells containing because they give vertical or substantially vertical electrodes and diaph-ragms.

l have found that the wandering of the hydroxyl ions in the vertical cells vcan be prevented in a veryy eilicient manner, even when the liquor in the cathode space contains a high vpercentage of alkali, by employing two,l or more, ilter diaphragms separated from one another, and by causing electrolyte 'to travel successively through each diaphragm in the same direction, that is, from the anode space to the cathode space.

It is not necessary that the whole quantity of the electrolyte which is drawn olf at the cathode be passed through each diaphragm. It is suficient if this is the case with one of the diaphragms, while the motion through the other, or others, can be reduced to a minimum without essentially reducing the yield. It is often advantageous if only a space, since then the finely divided precipitate which forms there can settle and does not tend to stop up the diaphragm pores.

One Way for instance of/carrying out my 'part of the total liquid flows from the anode invention is to allow a part of the liquidl to flow from the anode space throu gh two filter diaphragms into the cathode space, while the the hydrostaticpressure in the anode spacey and in the space between the two diaphragms. ln order to prevent the anode liquid from becoming exhausted, the anode space is continually supplied with fresh salt solution and the surplus is taken away in any suitable manner. i

f The drawing accompanying this specification represents diagrammatically, in vertical Section, a cell which can be used for the process of my invention. .u

In this drawing A represents the wall of the cell, B and are two vertical diaphragms, D is the anode and E is the cathode. The salt solution, for instance, a solution of sodium chlorid, flows through the pipe F, which has two outlets G and H so arranged that the liquid leaving G centers the anode space, while the liquid leaving H enters the space between the two dialution,

phragins B and C. The excess flows -out through the pipe K, while the chlorin is drawn oli' at v L and the hydrogen at M.

Now what I claim is 1. In the electrolysis of alkali chlorid solution, passing electrolyte successively through a plurality of substantially vertical filter diaphragnis in the direction from the anode to the cathode.

2. In the electrolysis of alkali chlorid solution, passing a part of the total electrolyte from the anode space through a plurality of substantially Vertical filter diaphragms to the cathode space.`

3. In the electrolysis of alkali chlorid solow from the anode space through two substantially vertical lter diaphragms into the cathode space, and introduclng an additional causing a part of the electrolyte toy and greater part of the electrolyte into the space between the filter diaphragrns.

4. In the electrolysis of alkali chlorid so-` lution, causing a part ofthe electrolyte to flow from the anode' space through two substantially vertical filter diaphragrns into the cathode space, and introducing an additional and greater part of the electrolyte into the space between the filter -diaphragms, and continually supplying the anode space with fresh solution of alkali chlorid and removing the surplus.

In testimony whereof I have hereunto set myhand in the presence of two subscribing witnesses.

WILHELM GAUS. Witnesses:

J. Anno LLOYD,

JOSEPH PEUFER. 

